The long-term goal of our research is to understand the structural basis of the complex processes that regulate the replication cycle of rotaviruses (RVs), which are the global pathogens causing life-threatening infantile gastroenteritis. During 2013-2016, our studies have answered several questions we previously asked, raised a new set of questions, and revealed novel concepts. As a result, we plan to pursue exciting new directions during the MERIT extension period (2018-2023) through four new AIMS. In pursuing these AIMs, we will use a multipronged approach involving glycan array screening, X-ray crystallography, single-particle cryo-EM, cryo-electron tomography of RV-infected cells, and functional assays.
In AIM1, considering that specific recognition of host cell glycans is a critical factor in host cell attachment and cross-species transmission, we will address new questions such as: (i) what is the glycan specificity in sialidase-insensitive animal RVs with zoonotic potential?; (ii) do these viruses show similar correlated glycan specificity with the human RVs we discovered in bovine and human P[11] RVs to cross the species barrier?; (iii) does glycan binding affect spike structure in the intact virion to influence downstream cell entry processes?; and (iv) do VP8*-specific human mAbs block glycan binding in human RVs?.
In AIM 2, our goal is to understand the structural aspects of the viral capping enzyme VP3, how it associates with the viral polymerase VP1 to gain insight into the mechanistic basis of endogenous transcription, and the possible role of VP3 in capsid assembly and genome encapsidation that occurs in the specialized replication factories called viroplasms. Experiments in AIM 3 are designed to probe further into understanding protein-protein interaction networks that regulate viroplasm-associated activities using structural techniques and cryo-ET of RV-infected cells at different time points post infection.
In AIM 4, our goal is to provide structure-based mechanistic insights into how RVs antagonize cellular antiviral responses by understanding structural aspects of RV proteins such as NSP1 that inhibit IFN pathways and the phosphodiesterase domain embedded in VP3 of group-A RVs that inactivates OAS/RNase-L pathway, and the dsRNA-binding domain in NSP3 of group-C RVs that inhibits dsRNA-dependent protein kinase.

Public Health Relevance

Rotavirus (RV) is the major pathogen of life-threatening diarrhea in children. With an innate ability of RVs to mutate and diversify, and to potentially the cross species barrier, it is unclear if the current vaccines will remain efficacious over time. Our proposed studies are designed to provide a structure-based understanding of how different strains of RV with recognized unique properties, interact with the host, counter the innate antiviral response, and replicate. We expect such an understanding will help develop better and new antiviral strategies.

National Institute of Health (NIH)
National Institute of Allergy and Infectious Diseases (NIAID)
Method to Extend Research in Time (MERIT) Award (R37)
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Special Emphasis Panel (NSS)
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Alarcon, Rodolfo M
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Baylor College of Medicine
Internal Medicine/Medicine
Schools of Medicine
United States
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Ramani, Sasirekha; Stewart, Christopher J; Laucirica, Daniel R et al. (2018) Human milk oligosaccharides, milk microbiome and infant gut microbiome modulate neonatal rotavirus infection. Nat Commun 9:5010
Criglar, Jeanette M; Anish, Ramakrishnan; Hu, Liya et al. (2018) Phosphorylation cascade regulates the formation and maturation of rotaviral replication factories. Proc Natl Acad Sci U S A 115:E12015-E12023
Hu, Liya; Sankaran, Banumathi; Laucirica, Daniel R et al. (2018) Glycan recognition in globally dominant human rotaviruses. Nat Commun 9:2631
Shanker, Sreejesh; Hu, Liya; Ramani, Sasirekha et al. (2017) Structural features of glycan recognition among viral pathogens. Curr Opin Struct Biol 44:211-218
Ramani, Sasirekha; Hu, Liya; Venkataram Prasad, B V et al. (2016) Diversity in Rotavirus-Host Glycan Interactions: A ""Sweet"" Spectrum. Cell Mol Gastroenterol Hepatol 2:263-273
Ogden, Kristen M; Prasad, B V Venkataram (2015) Quelling an innate response to dsRNA. Oncotarget 6:28535-6
Hu, Liya; Ramani, Sasirekha; Czako, Rita et al. (2015) Structural basis of glycan specificity in neonate-specific bovine-human reassortant rotavirus. Nat Commun 6:8346
Ogden, Kristen M; Hu, Liya; Jha, Babal K et al. (2015) Structural basis for 2'-5'-oligoadenylate binding and enzyme activity of a viral RNase L antagonist. J Virol 89:6633-45
Criglar, Jeanette M; Hu, Liya; Crawford, Sue E et al. (2014) A novel form of rotavirus NSP2 and phosphorylation-dependent NSP2-NSP5 interactions are associated with viroplasm assembly. J Virol 88:786-98
Venkataram Prasad, B V; Shanker, Sreejesh; Hu, Liya et al. (2014) Structural basis of glycan interaction in gastroenteric viral pathogens. Curr Opin Virol 7:119-27

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